1. Field of the Invention
The present invention relates to a spinning machine traveler, and more specifically, to a spinning machine traveler which is to be used in a spinning machine, such as a ring spinning machine (ring spinning frame) or a ring twisting machine (ring twisting frame), and which is formed into a predetermined shape by using a hard steel wire or an alloy steel wire.
2. Description of the Related Art
Recently, in ring spinning frames also, there is a demand for an increase in speed to achieve an improvement in productivity, and an ultra-high-speed spinning operation at a spindle RPM of not less than 20,000 rpm has been carried out. As the spindle rotational speed increases, the speed at which the traveler circles on the ring also increases. When the circling speed of the traveler increases, the frictional resistance between the ring and the traveler increases, and wear of the ring and the traveler is expedited, resulting in a rather short service life. Further, when the frictional resistance between the ring and the traveler increases, a large quantity of frictional heat is generated, making the parts themselves subject to damage and deformation and adversely affecting the take-up thread.
JP 7-81216 B discloses a traveler formed of steel wire which has undergone oxynitriding treatment in a gas-nitriding atmosphere in order to achieve an improvement in resistance to wear due to high speed running of the traveler, with a nitrogen compound layer of a thickness of 5 to 30 xcexcm being formed on the surface of the traveler.
JP 61-446 B discloses a structure in which, in order to achieve an improvement in the initial conformability with the ring, a solid lubricant coating of an epoxy resin containing molybdenum disulfide is formed on the surface of a metal traveler coming into contact with the ring.
Generally speaking, in a ring spinning machine, when the traveler is replaced with a new one, operating the machine from the start so as to attain the maximum rotational speed that is the same as in the normal spinning operation causes thread breakage due to seizure of the traveler, making it impossible to perform the normal operation. In view of this, in order to provide a track allowing the traveler to come into contact with the ring in a correct position at the start of use of the traveler (i.e., to form a worn portion), a running-in operation is executed in which the traveler operates at a rotational speed lower than the normal rotational speed (the rotational speed at the time of normal spinning operation) at the start of use, with the rotational speed being gradually increased.
In the case of the traveler as disclosed in JP 7-81216 B, in which an improvement in wear resistance is achieved by simply enhancing the hardness of the traveler surface, the service life after the formation of an appropriate working surface is relatively long as compared with a traveler which has undergone no wear resistance treatment. However, the initial conformability is rather poor, so that the requisite time for the running-in operation for forming an appropriate track on the traveler is rather long.
Also in the case of the traveler as disclosed in JP 61-446 B, in which an improvement in conformability has been achieved, when it is used in an ultra-high-speed rotation in excess of 20,000 rpm, it is necessary to perform a running-in operation for a long period of time, resulting in a deterioration in productivity and operability. In the case of the traveler as disclosed in JP 7-81216 B, the conformability at the time of ultra-high-speed operation is very poor, so that it is likely to cause thread breakage. Thus, it is of no practical value as a traveler to be used at 20,000 rpm or more.
Thus, to operate a ring spinning machine at ultra-high speed and in a stable manner, it is important that the requisite track allowing the traveler to run in a stable position can be formed without performing any running-in operation and that the slidability of the traveler after the formation of the track be satisfactory.
Generally speaking, in a ring spinning machine, the wear when the metal traveler slides on the metal ring is relatively small despite the fact that the taking-up of the thread is not effected while supplying a special lubricant material onto the slide surface between the traveler and the ring. It is assumed nowadays that this is due to the fact that part of the fiber (fluff) of the thread is detached and supplied onto the slide surface of the traveler, temporarily forming a lubricant film. The lubricant film, once formed, is gradually removed as a result of the gliding of the traveler, but fiber is newly supplied onto the slide surface to form a lubricant film, the cycle being repeated. And, when the attitude of the traveler is unstable, the lubricant film formed is subject to detachment, and in the condition in which there is no lubricant film, the wear of the traveler is expedited. Thus, to reduce the requisite time for the running-in operation, it is necessary for the traveler to be capable of gliding in a stable attitude in an early stage.
Recently, a traveler 20 as shown in FIG. 8 is in use as a traveler helping to enhance the stability in attitude during high speed running. A ring 21 associated with the traveler 20 has on the inner side a tapered surface 21a upwardly reduced in diameter and at its upper end an arcuate beveled portion. And, unlike the one formed by bending a steel wire substantially into a C-shape, the traveler 20 is formed of a steel wire to as to exhibit a flat rectangular sectional shape as shown in FIGS. 9A through 9C. It has a flat portion 20a capable of coming into slide contact with the tapered surface 21a of the ring 21 and a substantially C-shaped lock portion 20b connected to one end thereof. FIG. 8 is a partial schematic sectional view showing the relationship between the traveler 20 and the ring 21 associated therewith.
As shown in FIG. 8, during spinning operation, the flat portion 20a of this traveler 20 is in contact with the tapered surface of the ring 21 by the action of the centrifugal force; during stop of the spinning operation, the lock portion 20b is in contact with the outer surface of the ring 21. FIGS. 9A through 9C are schematic perspective views, of which FIG. 9A shows the traveler 20 with an appropriate track (wear track) 22 formed thereon; FIG. 9B shows the track 22 as formed by excessively wearing away the flat portion 20a; and FIG. 9C shows a condition in which the entire portion of the traveler 20 in slide contact with the ring has been excessively worn away.
With the conventional traveler 20, when spinning operation is performed at a spindle rotational speed of 20,000 rpm or more without performing any running-in operation, the states as shown in FIGS. 9B and 9C result, so that running-in operation is indispensable.
When performing ultra-high-speed spinning operation at a spindle rotational speed of 25,000 rpm or more, even if an appropriate track is formed in the early stage through running-in operation, an inappropriate wear as shown in FIGS. 9B and 9C may result depending on the traveler. And, such a traveler is likely to cause thread breakage.
It is necessary that the traveler replacement be effected simultaneously on all the spindles. Because if replacement were effected one by one, starting with the traveler worn in the early stage and frequently causing thread breakage, it would be necessary to reduce the spindle rotational speed for running-in operation each time a traveler is replaced, resulting in a deterioration in productivity. Thus, when the frequency of thread breakage reaches a certain degree, it has been the practice to replace all the travelers simultaneously including the ones whose service life has not expired yet. Thus, when the spindle rotational speed is as high as 25,000 rpm, the traveler replacement cycle is rather short; in the case of a traveler requiring running-in operation, this will lead to a reduction in productivity and bothersome thread breakage control.
The present invention has been made in view of the above-mentioned problem inherent in the prior art. Therefore, it is an object of the present invention to provide a spinning machine traveler which, even in the case of an ultra-high-speed spinning operation at a spindle rotational speed of 25,000 rpm or more, makes it possible to do away with running-in operation at the start of use of the traveler and which can attain an increase in service life.
To achieve the above-mentioned object, according to a first aspect of the present invention, there is provided a spinning machine traveler formed of steel wire or alloy wire into a predetermined shape, in which there are formed on a base material a nitrogen compound layer and a sulfide layer such that the nitrogen compound layer is on the base material side. The borders between the base material, the nitrogen compound layer, and the sulfide layer are not necessarily clear. The base material is turned into a nitrogen diffusion layer in which nitrogen is diffused at least in the portion thereof near the outer side, and, in many cases, in the vicinity of the border between the nitrogen compound layer and the sulfide layer, the sulfide component is diffused in the nitrogen compound layer.
In this spinning machine traveler, the hardness of the sulfide layer is the lowest, and the hardness of the nitrogen compound layer is the highest. The hardness of the base material is lower than that of the nitrogen compound layer but higher than that of the sulfide layer. When a new traveler is used, an appropriate initial track is formed in the early stage in the outermost, sulfide layer without having to execute running-in operation on the traveler. When the sulfide layer has been worn away, the nitrogen compound layer comes into contact with the ring. In this condition, the sliding force of the traveler is reduced as compared with the prior art, making it possible to perform spinning operation in a more stable manner. As a result, it is possible to perform spinning operation at a desired maximum speed from the start of use and to elongate the service life of the traveler.
According to a second aspect of the invention, there is provided a spinning machine traveler formed of steel wire or alloy wire into a predetermined shape, in which there are formed on a base material a nitrogen compound layer and a sulfide layer such that the nitrogen compound layer is on the base material side, and in which a solid lubricant material layer is formed on the outer surface of the sulfide layer. In this spinning machine traveler, a solid lubricant material layer is formed on the outermost layer of the traveler to exhibit a very small coefficient of friction. Further, its hardness is substantially lower (by one or two orders of magnitude) than that of the sulfide layer, so that the conformability of the traveler in the initial stage of use is improved, an appropriate track is formed in the early stage, and the initial slidability is further stabilized.
According to a third aspect of the invention, there is provided a spinning machine traveler according to the first aspect, in which the nitrogen compound layer and the sulfide layer are formed by sulphonitriding treatment. In this spinning machine traveler, a sulfide layer and a nitrogen compound layer with appropriate hardness can be easily formed.
According to a fourth aspect of the invention, there is provided a spinning machine traveler according to the third aspect, wherein the sulphonitriding treatment is a gas sulphonitriding treatment. In this spinning machine traveler, as compared with the salt bath sulphonitriding treatment, the conditions, etc. can be changed more easily, and no cyanide is required, so that there is no need to handle cyanogen, which is a toxic substance, making it unnecessary to perform cyanogen treatment operation.